The Joye 510 and the Joye eGo use the same type of atomizers, and if you buy the 510 cartomizers those will work on both as well. The main difference between the two besides size is the eGo has amazing battery life. I get a solid 6-10 hours on one battery. I know how you feel about it not looking like a real cigarette and that was actually a problem I faced when I first started. That problem actually pushed me back into smoking again. Probably wont do the same for you but just understand that the smaller the battery the shorter the battery life. With most of the "ANALOG" looking e-cigs you are lucky to get an hour and a half, in my experience anyways. Most of the time I was only getting 30-40 minutes. However if the looking like an analog is important for you try the KR808 from the VT store http://www.vaportalkstore.com/categories/Revolution-e-Cig/. I had a similar device and it wasnt too bad. However if you want Great vapor production, Great flavor, and Great battery life then I recommend the eGo. Honestly it's what is keeping me going. Also check out this review by GrimmGreen for the eGo. He is a no BS kind of reviewer, and you will get a good idea as far as the size of the eGo.
In all honesty though I wish I would have known about how great it would be to have a PV that has LONG battery life. It makes it so much easier. In my opinion its one less thing to worry about. If you add a drip tip to the mix it becomes even easier. Last but not least throw in a couple of cartos and its like vaping becomes such an easy habit to take on. The learning curve is still there but it becomes just so easy. More important to me than the PV looking like a cigarette is that I want it to be closer to the ease of use of just lighting up, and the set up I mentioned pretty much does that. Well as close as it can for an electronic device.